Liposomes as drug carriers.

Liposomes are artificially prepared vesicles made of lipid bilayer. Liposomes can be filled with drugs, and used to deliver drugs for cancer and other diseases. Amongst the various carrier, few drug carrier reached the stages of clinical trails where phospholipid vesicles (liposome) show strong potential for effective drug delivery to the site of action. Liposomes can be composed of naturally-derived phospholipids with mixed lipid chains or other surfactants. Liposome have covered predominantly medical, albeit some non-medical areas like bioreactor, catalysts, cosmetics and ecology. However,their predominance in drug delivery and targeting has enabled them to be used as therapeutics tool in fields like tumour targeting, gene and antisense therapy etc. Key-Words: Liposome, MLV, LUV, Application, Drug carriers Introduction The name liposome is derived from two Greek words: 'Lipos' meaning fat and 'Soma' meaning body. A liposome can be formed at a variety of sizes as unilamellar or multi-lamellar construction, and its name relates to its structural building blocks, phospholipids, and not to its size. Liposomes were first described by British haematologist Dr Alec D Bangham in 1961 (published 1964), at the Babraham Institute, in Cambridge. They were discovered when Bangham and R. W. Horne were testing the institute's new electron microscope by adding negative stain to dry phospholipids. 2 The resemblance to the plasmalemma was obvious, and the microscope pictures served as the first real evidence for the cell membrane being a bilayer lipid structure. Liposome are defined As “Liposome are simple microscopic vesicles in which an aqueous volume is entirely enclosed by a membrane composed of lipid molecule.” Various amphipathic molecules have been used to form liposome. The drug molecules can either be encapsulated in aqueous space or intercalated into the lipid bilayer. (Fig. 1) * Corresponding Author: E-mail: [email protected] Mob. 07898213986 A liposome is a spherical vesicle with a membrane composed of a phospholipid bilayer used to deliver drug or genetic material into a cell. Liposomes can be composed of naturally-derived phospholipids with mixed lipid chain like egg phosphatidylethonalimine or of pure components like DOPE (dioleolylphosphatidylethanolamine). Advantages of Liposome Provides selective passive targeting to tumour tissue (liposomal doxorubicin). 1. Liposome are increased efficacy and therapeutic index of drug (Actinomycin-D). 2. Liposome is increased stability via encapsulation. 3. Liposomes are biocompatible, completely biodegradable, non-toxic, flexible and nonimmunogenic for systemic and non-systemic administrations. 4. Liposome are reduction in toxicity of the encapsulated agent (Amphotericin B, Taxol). 5. Liposomes help to reduce exposure of sensitive tissues to toxic drugs. 6. Site avoidance effect. 7. Flexibility to couple with site-specific ligands to achieve active targeting. Disadvantages of Liposome 1. Production cost is high. 2. Leakage and fusion of encapsulated drug / molecules. 3. Sometimes phospholipid undergoes oxidation and hydrolysis like reaction. 4. Short half-life. 5. Low solubility. Review Article [Anwekar et al., 2(7): July, 2011]